Saturday, 4 September 2010

MRCP revision battle 2.2: Amiodarone and dronedarone


Amiodarone is a dirty, dirty drug, and as well has being dirty has a long half life of between 26 and around 126 DAYS.

It has a whole host of side effects to look out for in MRCP questions/real life:
- torsade de pointes
- ataxia
- alveolitis
- pulmonary fibrosis
- corneal microdeposits
- hepatitis
- metallic taste
- photosensitivity
- grey skin
- peripheral neuropathy
- and the classical THYROID PROBLEMS - if hypothyroid, amiodarone can be continued, if hyper, in general it should be stopped.

To try and remember this list I have a little mental cartoon of a man with a grey face, wearing sunglasses (photosensitivity) drinking from a metal can of beer (metallic taste and hepatits) and staggering because of his ataxia and peripheral neuropathy. He also has a goitre (thyroid problems) and is coughing (pulmonary fibrosis/alveolitis).  Due to the amiodarone prolonging his QT he goes into torsades and arrests; he then sees halos and glare (due to either him dying or his corneal microdeposits, depending on my mood)

The onset of amio is in hrs IV or 1-3 weeks when given orally.
As a practical aside remember when giving IV it is given in 5% dextrose and the doses tend to be 300mg over 20mins then 900mg over 24 hrs.

As an MRCP-irrelevant but randomly interesting aside DRONEDARONE has been proposed as a less toxic alternative to amiodarone ... essentially amiodarones brother but without his dirtiness.  Trials such as ADONIS and ATHENA (don't you just love drug companies acronyms?  yet another of my secret fetishes) showed that dronedarone did not cause thyroid problems or fibrosis.  Unfortunately, the ANDROMEDA trial showed it was dangerous in heart failure, and overall while amiodarone is 50-60% successful in treating AF dronedarone is only 30-40% successful.  So, since it costs more and works less, NICE have said no.

MRPC revision battle 2.1: SLE, Libman-Sachs and Jaccouds

After yesterdays achievement of getting through one whole question (which I got wrong) in my allocated hour of revision I approached today with some trepidation.  Happily, in 1.5 hours I got through 5 questions, I got 50% right and yesterday's thoroughness had already started to pay off as one of the questions involved oligoclonal bands in CSF (MS, NS NS, S S, GBS!)

So which topics do I want to recap from today's session?  The main one would definitely be SLE, and the side-dish to go with it for a clashing taste (probably metallic, if its side effects profile is to be believed) is amiodarone.

Revision battle 2.1: SLE
Revision battle 2.2: Amiodarone

Revision battle 2.1: SLE

Defined as a multi-system CTD with small vessel vasculits and non-organ specific antigens

Affects females far more than males (9:1), which I'm sure you all knew already

Is associated wiht HLA B8, DR2 and DR3

Is diagnosed by 4 of the following 11 criteria, which the OHCM helpfully suggests be remembered by A RASH POINTS MD:
  • Arthritis (non-erosive) of  2 or more joints
  • Renal disorder (either persistant >0.5g/l protein in urine or casts)
  • ANA + (occurs in 95% of cases)
  • Serositis - pleuritis or pericarditis
  • Haematological - haemolytic anaemia, leukopenia (WCC<4 on 2 occassions), lymphopenia (<1.5 on 2 occasions) or platelets <100
  • Photosensitivity
  • Oral ulcers
  • Immunological - anti ds DNA, anti SM or antiphospholipid antibody +
  • Neurological disorder
  • Malar rash
  • Discoid rash

3 best tests for monitoring SLE are:
  1. anti DS antibody titre
  2. decreased C3/C4
  3. raised ESR

Classical SLE led into brief foray to drug-induced lupus, which in contrast to SLE is commoner in men than in women.  It tends to be mild and rarely involves renal/neuro systems.  It generally resolves on stopping the culprit drug.

The common culprits are: PC M HIP: procainamide, chlorpromazine, minocycline, hydralazine, isoniazid, phenytoin.

Anti-histone antibodies are often present.

Happily SLE also threw up 2 more eponymous syndromes:

Libman-Sacks endocarditis: non-bacterial endocarditis associated with SLE, commonly affecting the MV.
Jaccouds arthropathy: a reversible deforming arthropathy due to capsular laxity.  As well as being seen in SLE it can feature in rhumatic fever, PD, and hypocomplementemic urticarial vasculitis.

Please click here if you wish to progress to the side-dish of amiodarone, battle 2.2!